CN203859678U - Switching power supply of photovoltaic grid-connected inverter - Google Patents

Abstract

The utility model discloses a switching power supply of a photovoltaic grid-connected inverter, which includes a transformer T1 and a PWM controller. The positive pole of the primary winding of the transformer T1 is connected to the power supply through a filter circuit, and the input ends of the PWM controller are respectively Connect the sampling circuit and the positive pole of the primary winding of the transformer T1, the output terminal of the PWM controller is connected to the negative pole of the primary winding of the transformer T1 through the field effect transistor Q1, and the B~H secondary windings of the transformer T1 are respectively connected to the inverter through the rectification filter circuit The driving circuit of the inverter, the relay and the fan, the DSP chip power supply terminal, the ARM chip power supply terminal, the first 485 communication interface, the second 485 communication interface and the CAN communication interface, and the feedback terminal of the PWM controller is connected to the DSP through the feedback circuit Chip power terminal. In the utility model, the switching power supply is arranged separately, and a certain distance is kept from each link of the inverter to avoid interference, and the stability of the inverter is improved.

Description

A switching power supply for a photovoltaic grid-connected inverter

technical field

The utility model relates to the field of photovoltaic grid-connected technology, in particular to a switching power supply of a photovoltaic grid-connected inverter.

Background technique

Solar photovoltaic power generation relies on solar cell components and utilizes the electronic properties of semiconductor materials to convert light energy into electrical energy. The grid-connected power generation system converts the received solar radiation energy into high-voltage DC through the photovoltaic array through high-frequency DC conversion, and outputs a sinusoidal AC current with the same frequency and phase as the grid voltage to the grid after inverting by the inverter; the inverter must be kept Only when the inverter is in a stable working state can it ensure that the high-voltage direct current generated by the photovoltaic array is inverted into a usable sinusoidal alternating current. The stable working state of the inverter needs to consider many factors, among which the power supply of the inverter is a very important one. factor.

The inverter used for 6KW photovoltaic grid connection needs to supply power to its drive circuit, relay and fan, power sampling circuit, DSP chip, ARM chip, two 485 communication interfaces, and CAN communication interface. For the switching power supply that supplies power to each link of the transformer, the measure adopted is to set the power circuit on the circuit board of each link separately, and the electromagnetic interference generated by the power circuit will easily affect the stability of each link.

Contents of the invention

The technical problem to be solved by the utility model is to provide a switching power supply for a photovoltaic grid-connected inverter, which can solve the problem that the current 6KW photovoltaic grid-connected inverter is equipped with power circuits on the circuit boards of each link, resulting in electromagnetic waves generated by the power supply circuits. Interference easily affects the stability of each link.

The utility model is realized through the following technical solutions:

A switching power supply for a photovoltaic grid-connected inverter, including a transformer T1 and a PWM controller, the positive pole of the primary winding of the transformer T1 is connected to the power supply through a filter circuit, and the input terminals of the PWM controller are respectively connected to the sampling circuit and the transformer The positive pole of the primary winding of T1, the output terminal of the PWM controller is connected to the negative pole of the primary winding of the transformer T1 through the field effect transistor Q1, and the B~H secondary windings of the transformer T1 are respectively connected to the driving circuit of the inverter through the rectification and filtering circuit , relay and fan, DSP chip power supply end, ARM chip power supply end, the first 485 communication interface, the second 485 communication interface and CAN communication interface, the feedback end of the PWM controller is connected to the DSP chip power supply end through the feedback circuit.

The sampling circuit includes the A secondary winding of the transformer T1 connected to the input end of the PWM controller after being rectified and filtered twice by the D9 diode, the C41 capacitor, the D10 diode, and the C42 capacitor, and one end is respectively connected to the PWM controller input end, and the other end is connected to the PWM controller input end. Zener diode D11 and capacitor C43 grounded at one end.

The filter circuit includes a ZR1 varistor connected in parallel to the two poles of the power supply, and an eighth resistor R8 and a C8 high-voltage ceramic capacitor connected in parallel to both ends of the varistor ZR1 after being connected in series. Both ends of the C8 high-voltage ceramic capacitor are connected in parallel with a series C9 capacitor and C10 capacitor, the two ends of the C9 capacitor and C10 capacitor are respectively connected in parallel with R9 resistor and R10 resistor, and the common end of the R8 resistor and C8 high-voltage ceramic capacitor is connected to the sampling circuit through the series connection of R11 resistor and R12 resistor.

The feedback circuit includes an optocoupler chip U3 whose output terminal is connected to the feedback terminal of the PWM controller through a C4 capacitor. The positive pole of the input terminal of the optocoupler chip U3 is connected to the power supply terminal of the DSP chip through the R4 resistor and connected to the voltage comparator U2 through the C7 capacitor. The fourth pin REF of the optocoupler chip U3 is connected to the negative pole through the C6 capacitor, the negative pole of the input terminal of the optocoupler chip U3 is connected to the third pin CA of the voltage comparator U2, and the fifth pin AN of the voltage comparator U2 is connected through a series connection The resistors R5 and R6 are connected to the power supply terminal of the DSP chip, and the common terminal of the resistors R5 and R6 is connected to the fourth pin REF of the voltage comparator U2 through the resistor R7.

Compared with the prior art, the utility model has the following advantages:

1. Set the switching power supply separately to keep a certain distance from each link of the inverter to avoid interference and improve the stability of the inverter operation;

2. The structure of each link of the inverter is more intuitive, the system structure is clearer, and the wiring is very convenient.

Description of drawings

Figure 1 is a circuit diagram of the PWM controller and the A and D secondary windings of the transformer T1.

Fig. 2 is a circuit diagram of the B secondary winding of the transformer T1.

FIG. 3 is a circuit diagram of the C secondary winding of the transformer T1.

FIG. 4 is a circuit diagram of the E secondary winding of the transformer T1.

FIG. 5 is a circuit diagram of the F secondary winding of the transformer T1.

FIG. 6 is a circuit diagram of the G secondary winding of the transformer T1.

FIG. 7 is a circuit diagram of the H secondary winding of the transformer T1.

Detailed ways

As shown in Figure 1, a switching power supply for a photovoltaic grid-connected inverter includes a transformer T1 and a PWM controller 1. The model of the PWM controller 1 is UC2845A. The positive pole of the primary winding of the transformer T1 is filtered The circuit 3 is connected to the power supply, the input terminal of the PWM controller 1 is respectively connected to the sampling circuit 2 and the positive pole of the primary winding of the transformer T1, and the output terminal of the PWM controller 1 is connected to the negative pole of the primary winding of the transformer T1 through the field effect transistor Q1, so The B~H secondary windings of the transformer T1 are respectively connected to the driving circuit of the inverter, the relay and the fan, the DSP chip power supply terminal, the ARM chip power supply terminal, the first 485 communication interface, the second 485 communication interface and CAN through the rectification and filtering circuit. Communication interface, the feedback end of the PWM controller 1 is connected to the power end of the DSP chip through the feedback circuit 4 .

The sampling circuit 2 includes the A secondary winding of the transformer T1 connected to the input terminal of the PWM controller 1 after being rectified and filtered twice through the D9 diode, the C41 capacitor and the D10 diode and the C42 capacitor, and one end is respectively connected to the PWM controller 1 input D11 zener diode and C43 capacitor with one end and the other end grounded. Considering that the sampling circuit 2 is not equipped with a voltage regulator chip, the fluctuation may be relatively large, so a D11 voltage regulator diode is added at the voltage output end.

The filter circuit 3 includes a ZR1 varistor connected in parallel to the two poles of the power supply, and an eighth resistor R8 and a C8 high-voltage ceramic capacitor connected in parallel to both ends of the varistor ZR1 after being connected in series. The C9 capacitor and the C10 capacitor, the two ends of the C9 capacitor and the C10 capacitor are respectively connected in parallel with the R9 resistor and the R10 resistor, and the common end of the R8 resistor and the C8 high-voltage ceramic capacitor is connected to the sampling circuit 2 through the series R11 resistor and the R12 resistor . Since the power input takes the DC input of the solar panel, the design of this switching power supply saves the rectification link compared with the traditional switching power supply. Considering the characteristics of the input voltage and current ripple of the solar panel The filter inductance is omitted, and only a C8 high-voltage ceramic capacitor is needed for filtering. Considering the wide dynamic range of the solar panel, the voltage stabilization filter capacitor is connected in series with C9 capacitor and C10 capacitor. For low-power power For electronic equipment, parallel resistors are usually not needed when capacitor series technology is used, but considering the stability of the system, this design connects R9 resistor and R10 resistor in parallel at both ends of C9 capacitor and C10 capacitor respectively.

The feedback circuit 4 includes an optocoupler chip U3 whose output terminal is connected to the feedback terminal of the PWM controller 1 through a C4 capacitor. The fourth pin REF of the device U2 is connected to the negative pole through the C6 capacitor, the negative pole of the input terminal of the optocoupler chip U3 is connected to the third pin CA of the voltage comparator U2, and the fifth pin AN of the voltage comparator U2 is passed The R5 resistor and R6 resistor connected in series are connected to the power supply terminal of the DSP chip, the common end of the R5 resistor and R6 resistor is connected to the fourth pin REF of the voltage comparator U2 through the R7 resistor, and the optocoupler chip U3 and the voltage comparator U2 respectively perform feedback signals. Isolation and conditioning. According to the characteristics of UC2845A needing feedback signal, the feedback signal is collected from the power supply end of DSP chip, because when the system works normally, the load of DSP part power supply remains basically constant, which is conducive to the stability of the whole switching power supply design.

The drive circuit of the inverter uses two drive chips, so the B secondary winding of the transformer T1 includes a B1 secondary winding and a B2 secondary winding respectively, which respectively supply power to the two drive chips.

Claims (4)

1. the Switching Power Supply of a photovoltaic combining inverter, comprise transformer T1, it is characterized in that: also comprise PWM controller (1), the armature winding of described transformer T1 is anodal by filter circuit (3) connection power supply, the input of described PWM controller (1) connects respectively the armature winding positive pole of sample circuit (2) and transformer T1, described PWM controller (1) output is connected in the armature winding negative pole of transformer T1 by field effect transistor Q1, B ~ H secondary winding of described transformer T1 connects respectively the drive circuit of inverter by current rectifying and wave filtering circuit, relay and fan, dsp chip power end, ARM chip power end, the one 485 communication interface, the 2 485 communication interface and CAN communication interface, the feedback end of described PWM controller (1) is connected in dsp chip power end by feedback circuit (4).

2. the Switching Power Supply of a kind of photovoltaic combining inverter as claimed in claim 1, it is characterized in that: described sample circuit (2) comprises the A secondary winding that carries out being connected in after twice rectifying and wave-filtering the transformer T1 of PWM controller (1) input by D9 diode, C41 electric capacity and D10 diode, C42 electric capacity, and one end is connected to D11 voltage stabilizing didoe and the C43 electric capacity of PWM controller (1) input, other end ground connection.

3. the Switching Power Supply of a kind of photovoltaic combining inverter as claimed in claim 1, it is characterized in that: described filter circuit (3) comprises the ZR1 piezo-resistance that is parallel to two poles, and the 8th resistance R 8 and the C8 high pressure ceramic disc capacitor that after series connection, are parallel to piezo-resistance ZR1 two ends, described C8 high pressure ceramic disc capacitor two ends are parallel with C9 electric capacity and the C10 electric capacity of series connection, described C9 electric capacity and C10 electric capacity two ends are parallel with respectively R9 resistance and R10 resistance, the common port of described R8 resistance and C8 high pressure ceramic disc capacitor is connected sample circuit (2) by the R11 resistance of series connection with R12 resistance.

4. the Switching Power Supply of a kind of photovoltaic combining inverter as claimed in claim 1, it is characterized in that: described feedback circuit (4) comprises that output is connected in the opto-coupler chip U3 of PWM controller (1) feedback end by C4 electric capacity, the input anode of described opto-coupler chip U3 connects dsp chip power end by R4 resistance respectively, the 4th pin REF that connects voltage comparator U2 by C7 electric capacity, by C6 electric capacity, connect negative pole, the input cathode of described opto-coupler chip U3 connects the 3rd pin CA of voltage comparator U2, the 5th pin AN of described voltage comparator U2 is by the R5 resistance of series connection, R6 resistance connects dsp chip power end, the common port of R5 resistance and R6 resistance is connected the 4th pin REF of voltage comparator U2 by R7 resistance.